Deep brain stimulation appears to help people with Parkinson’s disease over the long term, according to the first randomized clinical trial to look at its effect on patients’ motor symptoms three years later. The study is published in the June 20, 2012, online issue of Neurology®, the medical journal of the American Academy of Neurology.

For the study, 159 people with Parkinson’s disease randomly assigned to deep brain stimulation of the globus pallidus interna (GPi) or subthalamic nucleus (STN) of the brain were followed for three years. Participants reported motor symptoms in a diary for 30 minutes every half hour for two days before each of the six study visits. Medication use was allowed in the study.

“Past studies have had mixed results about which area of the brain benefits the most from deep brain stimulation,” said study author Frances M. Weaver, PhD, with Hines Veterans Administration Hospital and Loyola University Stritch School of Medicine in Maywood, Ill. “In our study, deep brain stimulation of both areas improved motor symptoms by 32 percent on average over the course of three years. However, deep brain stimulation of the GPi region of the brain was associated with a slower decline in thinking skills. More research will help us to find out whether medication or the deep brain stimulation was responsible for these differences.”

The study does have one major limitation, according to accompanying editorial author Michele Tagliati, MD, with Cedars-Sinai Medical Center in Los Angeles and a Fellow of the American Academy of Neurology. “A fairly large amount, or about 50 percent, of the initial participants could not be observed at three years due to the original study design and timeline. However, these data provide more reliable evidence that the improvement of motor symptoms of Parkinson’s disease by deep brain stimulation remains stable over the long term regardless of the area in the brain in which the deep brain stimulation occurs,” said Tagliati.

The study was supported by the Cooperative Studies Program, the Department of Veterans Affairs Office of Research and Development, and the National Institute of Neurological Disorders and Stroke, with additional funding from Medtronic Neurological, Inc.

To learn more about Parkinson’s disease, visit http://www.aan.com/patients.

The American Academy of Neurology, an association of more than 25,000 neurologists and neuroscience professionals, is dedicated to promoting the highest quality patient-centered neurologic care. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as Alzheimer’s disease, stroke, migraine, multiple sclerosis, brain injury, Parkinson’s disease and epilepsy. For more information about the American Academy of Neurology, visit http://www.aan.com or find us on Facebook, Twitter, Google+ and YouTube.